<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <style>
      /* 屏幕宽度小于等于768，网页背景色是粉色 */
      @media (max-width: 768px) {
        body {
          background-color: pink;
        }
      }

      /* 屏幕宽度大于等于1200，网页背景色是绿色 */
      @media (min-width: 1200px) {
        body {
          background-color: green;
        }
      }
    </style>
  </head>
  <body></body>
</html>
